import numpy as np


def is_symmetrical(arr):
    return NotImplemented


def is_triu(arr):
    return np.all(np.isclose(arr, np.triu(arr)))


def min_max(it):
    min_ = float('inf')
    max_ = float('-inf')
    for x in it:
        if x < min_: min_ = x
        if x > max_: max_ = x
    return min_, max_